DESCRIPTION (Applicant's Description): The Mammography Core is proposed for the collection, digitization, archival and analysis of mammography data. These data are essential to the completion of Projects 3 and 4, and will be examined in Projects 1 and 2. Over two thousand digitized mammogram were acquired from members of the cohort of breast cancer families during the most recent study period. Additional mammogram will be obtained as a component of Project 4's follow-up of the cohort of Breast Cancer Families. The result of this additional mammogram collection exercise will be the need to analyze as many as 8000 new mammogram. Core C will provide a service to the Program Project by: 1) managing the archive of digitized mammogram collected on the historical cohort of families, 2) collecting and digitizing mammogram as part of two follow-up surveys, 3) performing a clinical evaluation of each new mammogram for evidence of malignancy, 4) applying semi-automated quantitative image analysis algorithms that can be retrospectively applied to the entire collection of cohort mammogram to estimate percent density, and 5) implementing quality control procedures and studies to assure precision of breast density measurements. Breast density characteristics will be passed to the master database administered by Core B.